We take our dog with us on our our trips to SoCal. $200 round trip. The airline used to require a health certificate from the vet within 30 days of each trip. So, we were up to nearly $300 per trip.

Thankfully, the airline dropped the health cert. for each trip as long as we have a record of her immunizations with us.
It's gonna be painfully expensive when we get back to traveling abroad.